Hype created by the show forshadowing and spending time on the Azhor Ahai red herring, the Three Eyed Raven, the role of the dragons, the Long Night, Winter is coming, Valyrian steel, dragon glass... it was all used and resolved in the most mundane way possible. And the interviews done by the cast and crew just made things worse.
In hindsight I shouldnt be surprised. The runtimes were the first sign that the cast, crew, and HBO had been blowing smoke up our asses. I just didnt expect them to be blowing smoke up our asses about the entire Winter/Walker plotline.